Rotary knives of a type analogous to this invention are exemplified by structures shown in U.S. Pat. Nos. 3,269,010, 4,439,924 and 4,492,027. They are often used with a gauge for controlling the depth of cut, as shown, e.g., in U.S. Pat. Nos. 4,175,321 and 4,516,323. Such knives have a rotary ring-like or annular blade, sharpened at one axial end and incorporating gear teeth to form a ring gear portion at the other axial end. The ring gear portion is located and guided by a ring-like housing that is secured to a handle. The blade is driven by a pinion carried by the handle. A flexible cable driven by an external motor, or an air motor incorporated into the handle, drives the pinion.
Knives having blades like that shown in U.S. Pat. No. 3,269,010 are used for fine trimming, defatting, removing membrane and making thin cuts from a meat product. The cross-sectional curvature of that blade prevents making undesired deep cuts. That type of blade has in the past been supported in a ring-like split housing having an integral circumferential retaining lip and removal of the housing from the knife handle and expansion of the housing at the split were necessary to change blades. Heretofore, there has been no convenient arrangement for supporting such blades in the way trimming blades of conical cross section have been supported (see, e.g., U.S. Pat. No. 4,492,027), which allows convenient blade changing without split housings or housing removal.